To dream of using brakes represents your wish to slow down in a situation or relationship. You may not like how quickly a situation is progressing. A decision you've made may be having unforeseen consequences. It may also reflect a wish to take it easy or try something new.
To dream of your brakes not working may represent feelings about being unable to control or stop the direction a situation is going in your life. Feeling that life or certain decisions you've made are moving too quickly for your comfort level. Reduced control in waking life. A fear of getting into serious trouble if you don't stop a situation immediately.
Example: A man dreamed that his brakes weren't working. In waking life he was the CEO of a company and he began to feel that he was losing control of his company due to economic forces that pushed him to making decisions he didn't want to make and couldn't stop. He felt out of control of his company.